Traditional backpacks are worn on the user's back and incorporate a well-known two-strap system that requires one strap to be worn over each shoulder. While there are many variations on the strapping systems used in backpacks, nearly all backpacks rely upon this basic two-strap arrangement. On the other hand, a shoulder bag is a type of bag that is worn on the user's back, except with a shoulder bag only a single strap is slung over one of the user's shoulders. Whether a bag is worn as a backpack or a shoulder bag depends to some extent upon the type of activity in which the user is engaged. For instance, when a bag is being used while hiking it is advantageous to wear a backpack since the two-strap system provides a more stable and secure manner of carrying a load, and leaves both hands free for other uses. On the other hand, when shoulder bag is used it is easier to access the contents of the bag. But because the bag is less stable when worn as a shoulder bag than when worn as a backpack, it is often necessary to adjust the position of the strap or the bag itself.
A backpack may be worn as a shoulder bag--that is, with only one of the two straps slung over one shoulder. However, when worn in this fashion the unused backpack strap is often in the way. Furthermore, the backpack bag may not be designed for use in this manner and may not be very comfortable. A single-strap shoulder bag may not, of course, be worn as a two-strap backpack.
The advantages of a bag that is convertible from a traditional two-strap backpack arrangement into single-strap shoulder bag have been recognized for many years. These advantages include the ability to readily move the bag from one orientation to another and in this way relieve stress on the user's back by moving the bag from one carrying position to another. This can be important when the bag is used to carry relatively heavy or bulky loads, such as schoolbooks. Other advantages include the ability to wear the bag in different orientations depending upon the user's specific needs. For instance, the bag may be worn as a backpack when the user is hiking, and may be worn as a shoulder bag when the user has a need to access the contents of the bag quickly.
Ergonomic considerations in the design of backpacks are equally important as the basic design of the bag and the strap system. Over the past years designers have come to recognize that the usability of bags and luggage, like many other useful articles, can be greatly improved by designing the products in such a manner that pays attention to the how the user interacts with the products. By paying attention to how the bag is used, how it is worn, and by other factors, and by designing the bag in a manner that allows it to conform to the user's normal body positions and uses, the bag may be made much more "user-friendly" and comfortable.
However, while strap systems that allow bags to be converted from a backpack to a shoulder bag are known, ergonomic design principals have not been incorporated into past designs of such convertible backpacks and shoulder bags. As a result, known convertible backpacks/shoulder bags are unwieldy. To facilitate convertibility of a bag from a backpack into a shoulder bag, the bag must typically include a strap system that allows the bag to be used with either two straps--slung over each shoulder for the traditional backpack arrangement--or a single strap worn over one shoulder as a shoulder bag. But known convertible bags generally incorporate inconvenient strapping systems that are difficult to manipulate and convert. For example, when the bag is used as a shoulder bag, the second strap, which is necessary for use as a backpack, may be free and thus in the way. Other bags have strapping systems that are difficult to manipulate between the orientation required for the backpack mode and the orientation required for the shoulder strap mode.
In addition, the design of the bag itself must be taken into account when designing a bag that is to be worn as a backpack and as a shoulder bag. Since the bag rests on the user's back in a relatively different position when worn as a backpack, a traditional backpack design may not be comfortable when worn as a shoulder bag. Thus, a bag designed strictly for use as a backpack may not be well suited for use as a shoulder bag. Likewise, a bag designed for use only as a shoulder bag may not be very comfortable when used as a backpack.
One example of a convertible bag is shown in U.S. Pat. No. 4,153,092. In that patent the bag has a pair of straps that may be buttoned together to create a single shoulder strap, or alternately separately buttoned to the bag to create paired straps for use as a backpack. The button systems shown in this bag is an example of a system that would be difficult to manipulate. Moreover, the bag is not designed for comfortable transition from the backpack mode into the shoulder bag mode.
There is a need, therefore, for a bag that is easily converted from a backpack mode to a shoulder bag mode, and which is ergonomically designed so that the bag is comfortable to wear in either mode.
The bag of the present invention accomplishes these and other objects. The bag is generally triangular or teardrop shaped and incorporates padding on the lower panels where the bag rests against the user's back. The strap system of the bag of the present invention allows for easy multimode conversion between a single and double strap. Regardless of which mode, backpack or shoulder bag is selected, the upper end of the strap is attached to the top of the bag, near the apex of the triangular bag with a swivel connector. A zipper is sewn into the strap longitudinally along the length thereof, creating a longitudinally dividable strap having two arms when the strap is divided, and one arm when the strap is undivided. When the bag is being used as a backpack, the zipper is unzipped to create a strap having one upper end and two separate lower ends. Each lower end is separately connected to a ring on a lower edge of the bag. This creates a traditional two-strap backpack arrangement. When the bag is being used as a shoulder bag, the longitudinally split strap is connected along its length by closing the zipper. Both lower ends of the strap are disconnected from the rings on the lower edge of the bag and are connected to a ring on a side edge of the bag, thus creating a single-strap bag. This strap arrangement allows for easy conversion from one mode to another. The teardrop shape of the bag allows the bag to be worn comfortably in either orientation.